Lubrication system for rotary compressor



April 967 H. J. CASSIDY ETAL 3,312,387

LUBRICATION SYSTEM FOR ROTARY COMPRESSOR Filed Dec. 30. 1964 2Sheets-Sheet 1 April 4, 1967 H. J. CASSIDY ETAL LUBRICATION SYSTEM FORROTARY COMPRESSOR 2 Sheets-Sheet 2 Filed Dec. 30, 1964 rrlyjcasaa'agyUnited States Patent 3,312,387 LUBRICATION SYSTEM FOR ROTARY COMPRESSORHarry Joseph Cassidy, York, Pa., and William Donald Beck, Columbus,Ohio, assignors, by direct and mesne assignments, to Borg-WarnerCorporation, Chicago, Ill., a corporation of Illinois Filed Dec. 30,1964, Ser. No. 422,348 1 Claim. (Cl. 230-152) This invention relatesgenerally to compressors, and more particularly to improvements inlubrication systems for rotary, sliding vane compressors.

It is well recognized that rotary compressors offer many advantages overconvention-a1 reciprocating compressors, particularly in regard toimproved reliability and decreased vibration and noise. On the otherhand, the supply of a lubrication and cooling medium for the bearingsand seals in a rotary compressor often presents many problems,particularly in compressors used in refrigeration systems. For example,means for directly injecting lubricant into the compressor chamber,while commonly found in air compressors and vacuum pumps, has beenthought to be impractical in refrigerant compressors. The reason forthis is that the lubricant used in a refrigeration system contains ahigh proportion of dissolved refrigerant which is miscible with the oil.When the refrigerant and oil mixture is injected into the compressionchamber adjacent to the suction port, the refrigerant vaporizes out ofthe oil and expands under the relatively lower pressure conditionsexisting in this area. This results in the refrigerant vapor filling upthe suction volume and retarding the flow of suction gas into thecompression chamber. This action has the effect of reducing the capacityof the compressor and is detrimental to its operating efficiency.

Another problem inherent in the operation of the ordinary rotarycompressor is the failure to maintain a satisfactory flow of lubricantto critical components such as bearings and seals. It will beappreciated that the rotor, spinning at high rpm, tends to throw anylubricant outwardly from the rotational axis. As a result, it isdifficult to provide satisfactory flow of lubricant to the bearings andseals associated with the drive shaft which extends along the rotationalaxis of the rotor. According to the present invention, oil is forcedunder a positive'pressure into at least certain of the bearings andseals to insure that they are cooled and lubricated in a satisfactorymanner. 7

It is, there-fore, a principal object of the present invention toprovide an improved rotary sliding vane compressor especially adaptedfor use in a refrigeration system.

Another object of the invention is to provide a lubrication system for arotary compressor employing means for directly injecting a mixture ofoil and refrigerant into the compression chamber in such a way that asubstantial separation of the refrigerant from the lubricant is effectedwithout materially retarding the flow of suction gas into saidcompression chamber.

Still another object of the invention is to provide a positive means forinsuring satisfactory flow of lubricant to bearings and seals within thecompressor.

Additional objects and advantages will be apparent from a reading of thefollowing detailed description taken in conjunction with the drawingswherein:

FIGURE 1 is a cross-sectional view of a compressor constructed inaccordance with the principles of the present invention;

FIGURE 2' is a cross-sectional view taken along the plane of line 22 ofFIGURE 1; and

FIGURE 3 is a cross-sectional view taken along the plane of line 3- 3 ofFIGURE 1.-

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Referring now to the drawings, and particularly to FIGURE v1, thecompressor of the present invention comprises a housing, generallydesignated by reference character A, comprising a cylinder section 10,end plates 12 and 14, and a refrigerant gas chamber 16, all of saidparts being connected by suitable means, such as elongated cap screws17.

Housing A includes an internal cavity defined by a cylindricalperipheral wall 20 in cylinder section 10 and end walls 22, 24 formed bythe inwardly facing surfaces of end plates 12 and 14. Supported forrotation within the cavity by bearings 18, 19 is a cylindrical rotor 25which is mounted within the cavity in eccentric relation to theperipheral wall to provide a crescent shaped compression chamber 26between said peripheral wall and side walls 22, 24.

Communicating with opposite ends of the compression chamber 26 are asuction port 23 and a discharge port 29 through which refrigerant gas isrespectively admitted and discharged from the compression chamber.Discharge port 29 has associated therewith a discharge valve assembly 30of any conventional type. Rotor 25 comprises a cylindrical hub 32connected to a drive shaft 34 which is journalled for rotation bybearings 18 and 1-9 in end plates 12 and 14 respectively, and aplurality of vanes as received within a plurality of transverselyextending slots 38 in said hub, said vanes being reciprocatively movablewithin slots in the hub member. In order to maintain the vane tipportions in engagement with the peripheral wall 20, said vanes are urgedradially outwardly by a plurality of pins 40 which are operativelyassociated with each pair of diametrically opposed vanes. The pins 40,which extend through holes (not shown) in the hub and drive shaft,resiliently bias the vanes apart by means of small springs 42 receivedin complementary bores 43 in the under side of each vane.

As pointed out in the preliminary remarks, means are provided fordirectly injecting the lubricant and oil mixture into the compressionchamber 26 in such a way that the refrigerant released from the mixtureWill not fill up the suction volume to impede flow of the suction gastherein. vAs used herein, the term suction volume is meant to includeany portion of the compression cavity which is, at any position of thevanes, in fluid communication with the suction port 28. It will beappreciated that as the vanes sweep through the compression cavity inthe direction indicated by the arrow (FIG. 2), the volume, or extent ofthe cavity, open to the suction port 28 varies. The position of thevanes as shown in FIG- URE 2 is such that the vane adjacent to the loweredge. 28a of the suction port is just about to close oif the suctionvolume. Consequently, the suction volume at this point includes theentire volume in back of the leading vane, that is, the vane ahead ofthe one adjacent the edge 28a of the suction port. Therefore, the pointwhere suction is closed is the point in the cavity just ahead (in thedirection of rotation) of a leading vane when an adjacent trailing vanepasses the last point where the suction port intersects the compressioncavity.

Means for injecting the oil-refrigerant are provided by. a fluid passage46 communicating with the sump portion 47 of the refrigerant gas chamber16, said passage registering with a fluid passage 48 through thecylinder section. At opposite ends of the cylinder section, smallgrooves 49a, 4912 are provided in the face thereof to permit the dilutedlubricant to be injected into said compression chamber at the point,defined above, where the suction volume is closed. 7

Between the point where suction is closed and the discharge port, themaximum pressure reached at any time varies, depending on the radialdistance between the hub periphery and peripheral cavity wall 20.Immediately 9 adjacentto the discharge port, over compression occursjust before the discharge valve opens. On the other hand, at a pointjust beyond the point where the suction Volume is closed, the maximumpressure reached is substantially below discharge pressure. Since therefrigerant-oil mixture, is at discharge pressure, due to the factv thatrefrigerant vapor above the mixture in the sump is always at dischargepressure, the refrigerant in the oil vaporizes and is released from theoil when it is injected into the lower pressure area in the cavity.

At the same time, it can be seen that while the point at which therefrigerant-oil mixture is injected is under a lower pressure than thatwhich exists in the refrigerant gas chamber sump, the released vapor isnot permitted to expand :into the suction volume since the suctionvolume has been closed at this point by a vane passing the lower edge28a of the suction port.

As the rotor is driven in the direction of the arrow shown in FIGURE 2,radial movement of the vanes first increases until the vane is at apoint X intermediate the suction and discharge ports, said point beingdiametrically opposite to the point adjacent the discharge port wherethe hub is substantially contiguous with the peripheral wall 20. Fromthen on, the vanes collapse radially inwardly until they reach a pointjust beyond the discharge port 29.

This cyclical movement of the vanes produces a corresponding expansionand contraction of the volume of the spaces underneath the vanes, saidspaces being defined by the, end walls 22, 24,the.lower edge of eachvane, and the bottom of the vane receiving slots 38.

The oiland lubricant mixture which is injected through the injectionport flows through the clearance space between the ends of the rotor hub32 and the end walls 22, 24 of the compression chamber 26, and alsobetween the faces of the vane and the adjacent side portionsof the slotsinto which the vanes are received, ultimately filling up the spaceunderneath each vane when the vanes are substantially fully extended, ator near point X.

The end plate 12 is provided with a recessed portion 55 (the position ofwhichis indicated by dotted lines in FIGURE 2) in fluid communicationwith the space between the front bearing 18 and the rotary seal 58through fluid passage 56. As the spaces underneath the vanes approachtheir fully contracted position, which cor-responds to the maximumpressure of the lubricant in said spaces, the ends of said space passinto registered relation with recessed portion 55. The vanes, therefore,function as pumps into which oil is circulated and then compressed,finally being discharged through the passage 56 to the space between thebearing and the seal.

The gas chamber .portion, 16 of the housing A comprises a pair ofchambers 60, 62 provided by a partition shown in FIGURE 3. The chamberor compartment 60 shown in the upper left-hand corner of the figure is asuction chamber into which suction gas is passed from the evaporator.This suction gas compartment is in communication with the suction portshown in FIGURE 2. The. other compartment 62 is the gas dischargedepartment into which the gas under compression is passed through thedischarge valve assembly 30 and an opening 66 in the rear end plate 14.Discharge gas passes downwardly through a pair of oil separating devices68a, 68b and flows outwardly through the discharge passage 70 having anexternal connection 72 and a conduit leading to the condenser.

As the gas passes through the oil separating media, the oil coalescesand tends to separate from the refrigerant. Consequently, an oil levelindicated at L is formed in the lower or sump portion 47 of the gaschamber which communicates through passages 46 and 48 and oil injectionports 49a and 49b. Since the oil is under discharge pressure, there is apositive force acting on the oil to force it to the compression chamber.

While the ,unit described herein shows only a single passage in thefront end plate, it is obvious that additional passages may be providedin the rear end plate 14 for lubrication of the rear bearing. It willalso be appreciated that additional passages may be provided forlubricating other areas as required.

While this invention has been described in connection with a certainspecific embodiment thereof, it is to be understood that this is by wayof illustration and not by way of limitation; and the scope of thisinvention is defined solely by the appended claim which should beconstrued as broadly as the prior art will permit.

What is claimed is:

A compressor comprising a housing having a cavity therein, said cavitybeing defined by a generally cylindrical peripheral wall and opposed endwalls; a rotor including a generally cylindrical hub having a pluralityof substantially radially extending slots, and a shaft extending axiallyfrom said hub; means for rotatably journaling said rotor in said cavity,said means including at least one bearing supporting said shaft; saidhub, said peripheral wall, and said opposed end walls defining acrescent-shaped compression chamber, said rotor and said end wallsdefining clearance spaces therebetween; means defining suction anddischarge ports communicating with said compression chamber; a pluralityof vanes carried by said hub, said vanes being received in said slotsfor reciprocative movement so that the tip portions thereof aremaintained in engagement with said peripheral cavity wall, said vanesdefining a plurality of movable pockets therebetween, the volume of eachpocket expanding from said suction port to a point intermediate saidsuction and discharge ports and contracting from said intermediate pointin a direction toward said discharge port; means defining a space undereach of said vanes, the volume of which varies as said vanes reciprocatewithin said hub slots; means defining a fluid injection port openinginto said compression chamber at a point circumferentially spaced fromsaid suction port by a distance equivalent to the space between aleading vane and an adjacent trailing vane when said trailing vanepasses the end of said suction port; means for supplying refrigerantdiluted lubricant to said injection port, said lubricant flowing fromsaid compression chamber through said clearance spaces to the spacesunder each of said vanes to fill said spaces at a point when the volumetherein is at a maximum; and fluid passage means in one of said cavityend walls, said fluid passage means having a port at one end thereoflocated adjacent to the discharge port and registering with the spacesunder said vanes as the rotor is driven in the direction toward saiddischarge port, the other end ofsaid fluid passage means being in fluidcommunication with said bearing, whereby the lubricant under said vanesis pumped by the contraction of said vanes through said fluid passagemeans to said bearing as the spaces under said vanes are brought intoregistration with said fluid passage means port.

References Cited by the Examiner UNITED STATES PATENTS 1,732,039 10/1929Cuthbert 230-153 1,970,033 8/1934 Dennedy 230-152 2,013,777 9/1935Dennedy 230-152 2,275,774 3/1942 Kraissl 230-152 2,832,293 4/1958 Adamset al 230-207 References Cited by the Applicant UNITED STATES PATENTS1,928,300 9/1933 Peltier. 1,953,253 4/1934 Ogilvie. 2,455,297 11/1948Curtis et al.

DONLEY J. STOCKING, Primary Examiner. MARK NEWMAN, Examiner.

R. M. VARGO, -W. J. GOODLIN, Assistant Examiners.

